Long term evolution (LTE) based on 3rd generation partnership project (3GPP) technical specification (TS) release 8 is a promising next-generation mobile communication standard.
As disclosed in 3GPP TS 36.211 V8.7.0 (2009-05) “Evolved Universal Terrestrial Radio Access (E-UTRA); Physical Channels and Modulation (Release 8)”, a physical channel of the LTE can be classified into a downlink channel, i.e., a physical downlink shared channel (PDSCH) and a physical downlink control channel (PDCCH), and an uplink channel, i.e., a physical uplink shared channel (PUSCH) and a physical uplink control channel (PUCCH).
The PUCCH is an uplink control channel used for transmission of an uplink control signal such as a hybrid automatic repeat request (HARQ) positive-acknowledgement (ACK)/negative-acknowledgement (NACK) signal, a channel quality indicator (CQI), and a scheduling request (SR).
Meanwhile, 3GPP LTE-advanced (A) which is an evolution of 3GPP LTE is under development. Examples of techniques employed in the 3GPP LTE-A include carrier aggregation and multiple input multiple output (MIMO) supporting four or more antenna ports.
The carrier aggregation uses a plurality of component carriers. The component carrier is defined with a center frequency and a bandwidth. One uplink component carrier and one downlink component carrier are mapped to one cell. When a user equipment receives a service by using a plurality of downlink component carriers, it can be said that the user equipment receives the service from a plurality of serving cells.
The 3GPP LTE provides a PUCCH used for transmission of uplink control information. In order to maintain a low peak-to-average power ratio (PAPR) property, simultaneous transmission of the PUCCH and a PUSCH is not allowed. Therefore, if transmission of the uplink control information is requested in a subframe in which the PUSCH is scheduled, the uplink control information is transmitted by multiplexing the uplink control information to the PUSCH.
However, since a plurality of serving cells are used in a multi-carrier system, it may be ineffective to directly use a channel structure of a single-carrier system.